Sir Bernard Katz, FRS (26 March 1911 – 20 April 2003) was a German-born biophysicist, noted for his work on nerve biochemistry. He shared the Nobel Prize in physiology or medicine in 1970 with Julius Axelrod and Ulf von Euler. He was knighted in 1970.

Born in Leipzig to a Jewish family, Germany, he was educated at the Albert Gymnasium in that city from 1921 to 1929 and went on to study medicine at the University of Leipzig. He graduated in 1934 and fled to Britain in February 1935, the rise of Hitler having made his Russian Jewish heritage dangerous. He went to work at University College London, initially under the tutelage of Archibald Vivian Hill. He finished his PhD in 1938 and won a Carnegie Fellowship to study with John Carew Eccles at Sydney Hospital. He was naturalised in 1941 and joined the Royal Australian Air Force in 1942. He spent the war in the Pacific as a radar officer. He married Marguerite Penly in 1945 and returned to UCL as an assistant director in 1946. Back in England he also worked with the 1963 Nobel prize winners Alan Hodgkin and Andrew Huxley. Katz was made a professor at UCL in 1952 and head of biophysics, he was also elected to the Royal Society. He stayed as head of biophysics until 1978 when he became emeritus professor. At the age of 92, he died in London on 20 April 2003.